Process for gelling unsaturated polyester resins by addition of alcoholates of aluminum and titanium



United States Patent f 8 Claims. (31. 260-863) ABSTRACT OF THEDISCLOSURE This invention comprises methods of processing Bstage gelledunsaturated polyester resins. The un-- saturated polyester is admixedwith a free radical polymerization catalyst active only at temperaturesabove 60 C. and an alcoholate gelling agent selected from the groupconsisting of butyl titanate, aluminum alcoholate and an aluminumalcoholate chelate compound. The resulting mixture reacts attemperatures below 60 C. to form a storage stable deformable gel whichupon being shaped can be cured at temperatures above 60 C. to form ahard product.

This invention relates to a process of curing and manufacturing articlesfrom unsaturated polyester resins which comprises (a) the step offorming an unsaturated polyester resin into a storable andthermosettable gel which does not proceed in curing for a considerableperiod of time due to said resin containing a substance or substanceswhich cause gelation to said resin at a comparatively low temperatureand a substance or substances which cause initiation of polymerizationto said resin at a high temperature and (b) a subsequent step of curingsaid gel to hard product by heating.

This application is a division of application Ser. No. 6,372 filed Feb.3, 1960, now Patent No. 3,288,735.

The present invention is based upon the following findings: (l)unsaturated polyester resins, by adding to them a gelator selected from(a) ionic polymerization catalysts (b) gelling agents such asdiisocyanate and butyl titanate (c) both organic quaternary ammoniumcompounds and mercaptans, are converted to gels which are stable for aconsiderable period of time; (2) by adding free radical polymerizationcatalysts to said polyester resins prior to forming gels in the abovemanner, said gels when formed are rapidly polymerized to a hard polymerby heating. The gelator as employed herein is an agent causing gelatinto said resin.

In the conventional methods hitherto known, the curing of unsaturatedpolyester resins is carried out generally at a room temperature or underheating after they have been mixed with either "free radicalpolymerization catalysts or both free radical polymerization catalystsand promoting agents which act catalytically for the former. In such acase the resin scarcely increases in viscosity during a certain shortinduction period, but after the lapse of that period, they are convertedto gels becoming viscous in a very short time and finally setting to acured substance. Inasmuch as the above duration of time when the resinremains in a gel state is not longer than a few seconds to several tensof minutes, use of the resins in molding applications by utilizing itsgel state on an industrial scale are accompanied with many drawbacks,difiiculties and impossibilities.

Under the present invention, unsaturated polyester Patented Jan. 2, 1968resins may be maintained in stable gels for a considerably long periodof three days to three months or more. Thus such resins may be used as(a) coatings or adhesives in the form of filmy gels; (b) moldingmaterials as gels in the form of sheets or blocks or as particle sizedgels obtained by crushing or chopping said sheets or blocks; (0)laminating molding materials and materials for decorative plate assheet-form gels containing glass fibre, cloth, paper or cotton cloth.

The present invention is embodied in the following process. A mixture ofparts comprising an unsaturated polyester resin and an unsaturatedmonomer with 0.0 l-5 parts of a free radical polymerization catalyst ormixture thereof is mixed with either (a) an ionic polymerizationcatalyst or mixture thereof which causes gelation or (b) gelling agentswhich cause gelation by reacting with the terminal reactive groups ofthe resin or (c) both organic quaternary ammonium compounds andmercaptans, thereby gelling said mixture at a room temperature or below60 C. (this step being hereinafter referred to as the first stage):subsequently, the resulting reaction material in a gel state is heatedat a high temperature whereby it is cured to a hard infusible product(this step being hereinafter referred to as the second stage.) Theamount of the gelator to be added to 100 parts comprising theunsaturated polyester resin and an unsaturated monomer is as follows:(a) the ionic polymerization catalysts, 0.001 to 5 parts; (b) thegelling agents, 0.001 to 5 parts; (c) the organic quaternary ammoniumcompoundsand the mercaptans, 0.001 to 5 parts each.

The unsaturated polyester resin as employed in this invention is thekind of unsaturated polyester resin that is formed by the esterificationof polybasic acids including an alpha,beta-olefinically unsaturateddibasic acid with monoand/or polyvalent alcohols comprising mainlydivalent alcohols. The resin then is dissolved in a monomer having anunsaturated double bond which is copolymerizable withalpha,beta-unsaturated double bonds of the polyester resin. In thisinstance the monomer is usually added with a polymerization inhibitingagent or mixture thereof (which will be hereinafter referred to merelyas inhibitors). Typical saturated polybasic acids are the dibasic acidsincluding phthalic acid, terephthalic acid, adipic acid, sebacic acidand the like. Typical unsaturated dibasic acids are maleic acid, fumaricacid, citraconic acid, chloromaleic acid and the like. Examples ofdivalent alcohols are ethylene glycol, diethylene glycol, polyethyleneglycols, propylene glycol, mixed ethylene propylene glycols, 1,6-hexanediol, 1,3-butylene glycol, 2,2-dimethylpropane-1,3-diol, and thelike. Typical unsaturated monomers copolymerizable with the unsaturatedpolyester resins are styrene, acrylonitrile, ethylvinylbenzene,isopropenyl toluene, vinyl benzoate, methyl acrylate, methylmethacrylate, acrolein, dimethylstyrene and the like. To exemplify, atypical unsaturated polyester resin is obtained in the following manner:anhydrous maleic acid, anhydrous phthalic acid, ethylene glycol, andpropylene glycol in amounts corresponding to a respective mole ratio of0.5:0.5:0.55:0.55 are reacted at C. until the acid value of the mixturereaches 50, and unsaturated polyester resin thus vformed (100 parts) isthen dissolved in 50 parts of styrene monomer to which 0.05 part ofhydroquinone has been added as an inhibitor.

The inhibitor as employed in this invention is such an agent or mixturethereof which acts to inhibit free radical polymerization of said resinand monomer in course of gelation, and is selected from: (a) phenolssuch as hydroquinone, para-tertiary-butylcatechol, pyrogallol,trinitrophenol, 4 ethylcatechol, 3 phenylcatechol, 3-isobutylcatechol,etc. (b) quinones such as quinone, tetrachloro-p-quinone, toluquinone,quinhydrone, etc. (c) aromatic amines such as N,N-di-beta-naphthyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine,phydroquinone-diphenylamine, p-methyl-p-sulphonamide phenylamine, etc.(d) amine salts such as tributylamine hydrochloride, etc. (e) ascorbicacid (f) trinitrobenzene (g) sulphur compounds and other free radicalpolymerization inhibitors known in the art.

The free radical polymerization catalys as employed in this invention issuch a catalyst in the presence of which a copolymer is formed betweenalpha,beta-unsaturated double bonds and unsaturated monomers which arecopolymerizable therewith by the formation of free radicals. Toexemplify, typical free radical polymerization catalyst are benzoylperoxide, lauroyl peroxide, tertiary-butyl perbenzoate, methyl ethylketone peroxide, azobisisobutylonr trile, etc.

The ionic polymerization catalyst as employed in this invention is sucha catalyst which causes polarization which initiates polymerization insaid resin. The catalyst which gives positive electric charge to theopposite side of the carbon atom in the-double bonds which iscoordinated with said catalyst is called a cationic polymerizationcatalyst, whilst that which gives negative electric charge is' called ananionic polymerization catalyst. The former i.e., the cationic catalyst,is typified by inorganic strong acids,'aluminium chloride, aluminiumfluoride,

boron trifiuoride, ferric trichloride, stannic tetrachloride, andtitanium tetrachloride; the latter, i.e.,' the anionic catalyst istypified by alkali metal alkyl compounds, alkali metal-amides, alkylaluminium compounds, alkaline earth metal alkyl compounds,triphenylmethyl bromide and Grignards reagents.

The gelling 'agen as employedin this invention is selected from thefollowing; (a) a compound, or mixture of compounds, which contain morethan two radicals in each molecule that can be chemically bonded withthe unsaturated polyester by reacting with the active hydrogen atoms ofthe terminal carboxyl groups or the terminal hydroxyl groups of saidester at a temperature below 60 C.; (b) a compound, or mixture ofcompounds, which contain more than two groups in each molecule that canbe chemically bonded with the unsaturated polyester by reacting with theterminal alkoxyl groups of said polyester through an ester interchangeat a temperature below 60 C. To exemplify, a typical gelling agent istolylene diisocyanate, hexamethylene diisocyanate, triphenylmethanetriiocyanate, polyaryl polyisocyanate, tetrakis (hydroxymethyl)phosphonium chloride, carbonyl chloride, halides of elements classifiedin Groups No. 3 to No. 8 of the periodic table, or alcoholates and theirderivatives of elements classified in Groups No. 3 to No. 8 ofthe'periodic table including butyl titanate, aluminium alcoholate,aluminium alcoholate-ethyl acetoacetate chelate compound, and aluminiumalcoholate-acetylacetone chelate compound.

'The organic quaternary ammonium compounds as employed'in this inventionare represented by the formula:

wherein (1) R R R and R4-=3I6 selected from the following organicfunctional groups; (a) saturated or unsaturated hydrocarbon groupshaving 1 to 18 carbon atoms such as butyl, methyl, propyl, isopropyl,primary-, secondaryor tertiary-butyls, amyl, octyl, cetyl, dodecyl,oleyl, stearyl, phenyl, benzyl, tolyl; (b) such organic acid groups,i.e., acyl groups, as have 1 to 18 carbon atoms, e.g., lauroyl, benzoyland palmitoyl; (c) halogen and hydroxy derivatives of the groups setforth in (a) and (b) above; (d) cyclic groups wherein R R R and R arebonded together in one or two pairs to form a cyclic structure such asin pyridinium salt; (e) organic quaternary ammonium salt groups bondedby' divalent hydrocarbon e.g., alkylene groups, to the nitrogen shown inthe above formula, such as in ethylenebis (trimethyl ammonium); and (2)wherein X is selected from (a) residual acid groups of non-oxidizablestrong, inorganic acids such as hydrogen chloride, sulphuric acid,phosphoric acid, hydrogen bromide, hydrogen iodide; (b) residual acidgroups of comparatively strong organic acids such an acetic acid, oxalicacid, citric acid, malonic acid, chloroacetic acid; (c) residual acidgroups of hydroxycarboxylic acid such as lactic acid; or (d) thehydroxyl group. The organic quaternary ammonium compounds asabove-mentioned are actually employed not only singly but also asmixtures thereof.

The mercaptans as employed in this invention in combination with thequaternary ammonium compounds are monovalent and divalent mercaptansselected from the following: (a) the mono-mercaptans; their organicgroups being selected from the following; (i) alkyl groups h'avingl to20 carbon atoms such as methyl, ethyl, primary-, secondaryortertiary-butyls, dodecyl, cetyl; (ii) halogen,- amino or nitroderivatives of groups selected from (i) above; (iii) aryl groups such asphenyl and benzyl; (iv) unsaturated hydrocarbons such as allyl andbutenyl; (b) the di-mercaptans; alkane dithiols with 2 to 12 carbonatoms such as ethanedithiol and butanedithiol.

When the ionic polymerization catalyst is-admixed with the mixture ofunsaturated polyester resin, unsaturated monomer, inhibitor and freeradical catalyst, the resin mixture polymerizes at room temperature to agel without diminishing the effects of the inhibitor. Thereby theproduct of this initial polymerization has a low molecular weight, whichenables the resulting unsaturated polyester resin mixture to bemaintained in a stable gel state for a long period.

The gelling agent also does not act upon the unsaturated monomer,inhibitor or free radical catalyst present in the unsaturated polyesterresin mixture but reacts with the active hydrogen atoms of the terminalhydroxyl and carboxyl groups of the polyester resin or it causes anester interchange with the terminal alkoxy groups of the resin, therebycausing cross-linkages between said resin and the gelling agent. Thisleads to the formation of a stable gel state. Since the inhibitorremains effective in the resin mixture, the resin mixture can bemaintained in a gel state for a long period of time without incurringany substantial copolymerization between the alpha,beta-unaturateddouble bonds and the unsaturated monomers in said resin mixture.

When organic quaternary ammonium compounds and mercaptans are added tothe unsaturated polyester resin mixture, the resin mixture is convertedto a gel at a room temperature in a short period of time by theformation of cross-linkages between the alpha,beta double bonds of thepolyester resin and the unsaturated monomers in the mixture. In thiscase, the resin is maintained in a stable gel state since thecross-linkages do not proceed any further beyond the gel stage. As oneembodiment of this invention, the organic quaternary ammonium compoundsare first mixed with the polyesterresin and unsaturated monomer mixture,since said compounds act themselves as inhibitors, and any otherinhibitor may not necessarily be added where said ammonium compoundshave been added to the polyester resin in an amount of over 0.05 partfor every parts composed of said resin and said monomer.

The time required for complete gelation in this invention can beadjusted by varying (a) the concentration of the ionic polymerizationcatalyst when it is employed; (b) the concentration of the gelling agentwhen it is employed; (c) the cencentration of each of the organicquaternary ammonium compounds and the mercaptans when they are employed.In the above (c) case, the time required for complete gelation can belessened by adding 0.0001 to 0.1 part of metallic organic salts which issoluble in the unsaturated polyester resin and the monomer (preferablycopper, cobalt, manganese, calcium or lead naphthenates) for every 100parts comprising said resin and the monomer. In this instance, as oneway of embodying this invention, the above metallic salts can be firstadded to the polyester resin and the monomer prior to the addition ofthe free radical polymerization catalysts, and the organic quaternaryammonium compounds and the mercaptans.

'In gelling the unsaturated polyester resin according to the threemethods of this invention hereinabove mentioned, the free radicalpolymerization catalysts remain intact intimately mixed with the resinmixture after the resin mixture has been converted to a gel (in thefirst stage) by the previous addition of said gelation catalysts to theresin mixture. The resin mixture in the gel state is then cured in thesecond stage by heatin at 70 to 150 C. for a duration of 30 seconds tominutes.

In the following there are described in detail certain practicalapplications of this invention.

(A) As coating materials: the gel in film form is obtained in the firststage and then is attached under pressure to the object to be coated byheating in the second stage. By this treatment the resin gel in a filmstage tightly adheres to the object and is cured to a coating excellentin surface hardness and resistance to chemicals. Furthermore, the filmin the gel state obtained from the first stage of the process of thisinvention can be stored for a considerable period of time in the gelstate without curing to hard, infusible products. At any time duringthis period it can be subjected to the second stage treatment withoutfurther formulating whenever one chooses to form the final, curedproducts.

. (B) As a material for forming rodor bar-form, tubular-form, cord-form,or sheet-form products: the gel obtained from the first stage issubjected to pulverization and subsequently is extruded into a rod orbar-form, tubular-form, cord-form, or sheet-form gel. The unsaturatedpolyester resin mixture in the liquid state with or without admixed fillng materials and/ or reinforcing materials can be similarly subjected toextrusion, thereby obtaining gels in similar forms. Thereafter theformed gels are subjected to curing by heating.

The gels in cord-form, sheet-form, barand rod-forms obtained from thefirst stage of this invention can be stored for a considerable period oftime as so-called prepreg molding materials without curing to hard,infusible products. At any time during this period they can be subjectedto the second stage treatment whenever one chooses to obtain the finalcured product. The tubular-form gel obtained from the first stage isvery much suited for the continuous production of pipes.

(C) As molding materials for making small molded products: liquidunsaturated polyester resin mixture is poured into a hollow horizontalcylinder wherein it is subjected to rotation while it gels, there-byforming a bar or tubular gel which, after being cut or punched todesired forms, is subjected to pressed molding to obtain small moldedproducts such as buttons.

(D) As materials for making so-called pro-mix compounds: the unsaturatedpolyester resin mixture (itself or admixed with filling agents)impregnated onto with continuous fibrous reinforcing materials (such asglass roving) is subjected to gelation and thereafter it is cut into adesired length to obtain straw-form pre-mix compounds. The compounds arethen molded and cured under heat and pressure to produce molded article.When the liquid unsaturated polyester resin mixture, which may or maynot contain filling materials, is mixed in a mixer with chopped glassfibers and gelation is brought about, puffy-form pre-mix'compounds areobtained. These premix compounds can stably be stored for a considerableperiod, during which period they can be molded at any time one chooses.

(E) As materials for manufacturing large-size molded products such asboat-hulls and automobile bodies: both a fibrous reinforcing materialsuch as glass roving cut into the desired length and the liquidunsaturated polyester resin mixture are sprayed simultaneously onto aform to obtain a product in the desired form. The product is thenallowed to gel and thereafter it is cured under heat and pressure. Thusthe pre-forming of large-size molded products'can be elfectuated easilyand economically in the above manner. Besides, the 'pre-formed, gelledbut uncured products can be stored for a considerably long period oftime.

(F) As materials for making other products: (i) Particle-size orsheet-form gels as molding materials which do not contain reinforcing orfilling materials are put in a metallic mold, wherein they are pressedat 330 kg./cm. under heating at -150 C. for 30 seconds to 15 minutes toobtain a hard molded product. (ii) Sheet-form gel which contains glassfibre, paper, cotton cloth, knitted bamboo or knitted wood-plats isformed into contoured sheets having the desired curved surfaces, and thecontoured sheets are then heated to 80'l50 C. for 30 seconds to 15minutes to cure them into hard, strong, laminated molded products havingthe desired curved surfaces. The gels obtained from the first stage ofthis invention can be stably stored for a long period as s'o-calledpre-preg molding materials, during which period they can be subjected asdesired to the second stage treatment at any time to obtain hard, finalproducts.

The instant invention can equally be applied to and embodied in not only(a) the unsaturated polyester resin mixture itself but also (b) mixturesof the resin mixture with calcium carbonate, barium sulphate, clay,metallic powder, glass powder, coloring agents or other pulverizedsubstances and (c) resin mixtures to which have been added such fibroussubstances as glass fibre, cotton fibre, jute fibre, asbestos andsynthetic fibres.

' The following examples describe in detail certain embodiments orillustrations of the instant invention. However, it should be understoodthat the invention is not confined in scope to these examples. In theexamples all parts are by weight.

Example 1 parts of unsaturated polyester resin obtained by heating at180 C. a mixture of anhydrous maleic acid, anhydrous phthalic acid andpropylene glycol in an amount corresponding to a molecular ratio of0.5:05: 1.1 until the acid value of the material reached 50, wasdissolved in 50 parts of styrene to which 0.05 part of hydroquinone hadbeen added as an inhibitor. After mixing the solution with 1 part ofbenzoyl peroxide, there was 0.8 part of boron triluoride acetic acidcomplex (add-uct). The resulting mixture was kept standing at 2030" C.for 10-30 hours to obtain a sheet in a gel state. The sheet was storedin a gel state for 3 weeks at 20-30 C., and thereafter it was heated ina metallic moldat C. for 5 minutes to obtain a hard, infusible moldedproduct.

Example 2 100 parts of unsaturated polyester resin obtained by heatingat C. a mixture of anhydrous maleic acid,

anhydrous phthalic acid and propylene glycol in an amount correspondingto a molecular ratio of 0.5:0.5: 1.1 until the acid value of thematerial reached 50, with which 0.2 part of trimethyl benzyl ammoniumchloride, 0.00001 part of copper naphthenate, and 50 parts of styrenehad been mixed, was added with 0.8 part of caproyl peroxide. Then 3parts of pearl essence and 0.03 part of butyl mercaptan were added withagitation to the mixture. The resulting mixture was then cast in ahorizontal cylinder under rotation at, a temperature of 35 C. for onehour to obtain a hollow pipe in a gel state with pearl lustre. The pipewas then cut longitudinally into sheets. Each sheet was able to bestored in a gel state at 2530 C. for over one month. The sheets werethen put into metallic molds either as sheets, or after having beenpulverized to particles, and then cured" under heating at 120 C. andpres- 7 v sure for 3 minutes to obtain molded products such as hardbuttons.

Example 3 100 parts of unsaturated polyester resin obtained by heatingat 180 C. a mixture of anhydrous maleic acid, anhydrous phthalic acidand propylene glycol in an amount corresponding to a molecular ratio of0510.5: 1.1

compound. The compound was stored for 4 weeks with- V out hardening orcuring. It was then put into a metallic mold wherein it was molded at120 C. and at a pressure of 50 kg./cm. for 3 minutes into a moldedproduct having excellent mechanical strength. Characteristics of theproduct were: flexural strength kg./mm. tensile strength 18 kg./mm. andimpact strength 86 kg.cm./ cm.

Example 4 66.7 parts of unsaturated polyester resin obtained by heatingat 180 C. a mixture of anhydrous maleic acid, anhydrous phthalic acidand propylene glycol in an amount corresponding to a molecular ratio of0520.5 :1.1 until the acid value of the material reachedSO, wasdissolved in 33.3 parts of styrene to which 0.03 part of hydroquinonehadbeen added as an inhibitor. After mixing the solution with 1 part oftertiary butyl perbenzoate and 2 parts of triphenyl methanetriisocyanate, and the mixture, after having been impregnated on glasscloth, formed into a sheet, was placed between polyethylene film, rolledand kept standing for 20 hours at 2030 C. Thereby a tack-free moldingmaterial in sheet form was obtained. This was stored stably for days,and then it was laminated in ten plies and was placed in a metallic moldwherein it was subjected to pressing at 120 C. and 30 kg./cm. for 5minutes to obtain a hard, laminated, molded product.

Example 5 A solution comprising 66.7 parts of the unsaturated polyesterresin, 33.3 parts of styrene and 0.03 part of hydroquinone similar tothat in the preceding example was mixed with 0.5 part ofparachlorobenzoyl peroxide and 2 parts'of aluminium triisopropylate,whereby the resulting mixture was converted to a gel in a few minutes ata room temperature. It was stably stored for a fortnight at 20 to 30 C.Then it was pulverized to a suitable particle-size one and was placed ina metallic mold wherein it was subjected to pressing at 130 C. and 30kg./cm. for 3 minutes whereby a transparent and infusible hard moldedproduct was obtained.

Example 6 100.03 partsof the solution similar to that inExample 4 wasmixed with 0.7 part of benzoyl peroxide and 4 parts of butyl titanate,and the mixture, after having been impregnated on paper or cloth whichbear patterns, was formed into a sheet, which was placed on thicknessand a stainless lustrous plate was placed on 8 4 it. Then it wassubjected to pressing at C. and 15 kg./cm. for 10 minutes whereby thematerial tightly adhered to the plywood plate. Thus a beautifuldecorative plate with a lustrous surface was obtained.

Example 7 100.03 parts of the solution similar to that in Example 4 wasmixed with 3 parts of pearl essence, 0.8 part of lauroyl peroxide and 4parts of aluminium diisopropylateethylacetoacetate chelate compound,whereby the resulting mixture wasconverted to a gel in 2 hours at aroomtemperature. It was stored stably for about a fortnight at a roomtemperature. The gel, after having been chopped to suitable-sizedpieces, was placed in a metallic mold wherein it was subjected topressing at 120 C. and 30 kg./cm. for 3 minutes to obtain a resinousproduct with pearl lustre. Manufacture of buttons in this mannerresulted in a saving of materials by about 20% compared with theconventional centrifugal method, namely the casting in a horizontalcylinder under rotation. I

What is claimed is:

1. The process of manufacturing articles from curable olefinicallyunsaturated polycarboxylic acid/polyol polyester resins which comprisesthe steps of, (A) mixing said resin with (a) a monomeric organiccompoundhaving an olefinic double bond which reacts with the ole finicunsaturated bond of said polyester resin in copolymerization by a freeradical polymerization catalyst, (b)

at least one free radical polymerization catalyst which is active onlyat temperatures above 60 C. selected from the group consisting ofbenzoyl peroxide, parachlorobenzoyl peroxide, di-tertiary-butylperoxide, tertiary butyl perphthalic acid, 2,2-bis(tertiary butyl)peroxybutane, tertiary-butyl peracetate, dicumyl peroxide, lauroylperoxide, azo-bis-isobutylonitrile, and azo-bis-phenyl ethane, theamount of said free radical polymerization catalyst being 0.01 to 5parts by weight for every 100 parts comprising said resin and saidmonomer, and (c) an alcoholate selected from the group consisting ofbutyl titanate, aluminum alcoholate and an aluminum alcoholate chelatecompound, the amount of said alcoholate being 0.001 to 5 parts by weightfor each 100 parts by weight comprising said resin and said monomer; (B)allowing the resulting resinous mixture to react at a temperature belowabout 60 C. to form a deformable gel which is stable toprolongedstorage; and (C) thereafter subjecting said gel to a temperature aboveabout 60 C. to cure said gel to a hard product.

2. The process as claimed in claim 1 wherein the gel is shaped into anarticle prior to heating to cure.

3. The process as claimed in claim 1 wherein said gel is formed in arotating, horizontal'cylinder.

4. The process as claimed in claim 1 wherein said gel is formed in amixer in the presence of a fibrous filler.

5. The process as claimed in claim 1 wherein an inert film sheet iscoated with said resinous mixture prior to formation of said gel, thegel after it is formed on said film is attached to an object underpressure, and the film is stripped oif after curing.

6. The process as claimed in claim 1 wherein fabrics are impregnatedwith said resinous mixture prior to formation of a gel and theimpregnated fabrics are formed into contoured shapes after gelation butbefore heating to cure whereby after heating contoured articles areformed.

7. The process as claimed in claim 1 wherein continuous fibers areimpregnated with said resinous mixture prior to the formation of a gel,the impregnated fibers are cut into pieces each 3 mm. to mm. in lengthafter gelation and are molded and cured under pressure 9 1G materialonto a preformed mold, allowing said mixture 2,892,780 6/1959 Rinse260-75 to gel and subsequently heating the gel thus obtained 3,227,6651/1966 Fourcade et a1 2602.5 under pressure to form a molded product.FOREIGN PATENTS References Cited 5 801,795 9/1958 Great Britain. UNITEDSTATES PATENTS GEORGE F. LESMES, Primary Examiner. 2,429,060 10/1947Hoover et al. 260-865 2,628,209 2/1953 Fisk 260 863 TILLMANi Examme"2,680,108 6/1954 Schmidt 260- 75 I. T. GOOLKASIAN, Assistant Examiner.

